Advanced Tactics is developing an autonomous helicopter that could land outside a battlefield, transform into a car, and drive into a dangerous area where soldiers need help.

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Real-life transformers may be coming to the U.S. Army, and these helicopter-cars could provide a futuristic way to provide medical care on the battlefield.

California-based Advanced Tactics has proposed its Black Knight Transformer as an autonomous casualty-evacuation vehicle for the U.S. Army. It's not the only autonomous helo coming out of research labs around the country and going into military testing. But what sets the Black Knight apart is its ability to fly to a landing zone nearby the battlefield and then transform into a ground-bound ambulance.

"The driving capability gives you the ability to land somewhere safe, drive to where the casualty needs to be picked up, drive back out and fly away safely without taking off near combat action," Advanced Tactics chief engineer Rustom Jehangir says.

In addition to being a transformer, the Black Knight stands apart from other unmanned rotorcraft by virtue of its design. Advanced Tactics calls it the world's largest multicopter. The Black Knight scales up the basic idea you'd see on the small quadrotor RC helicopters now available for recreation and increasingly as camera/video platforms.

The Black Knight has eight boxer-configuration four-cylinder gasoline engines with seven-foot, two-blade rotors that connect to the body of the helo via A-arms. The engines drive the rotors directly, with no conventional helicopter transmission, swash plate, or tail rotor. To remain stable, Black Knight uses differential thrust between opposing sets of prop-rotors controlled through Advanced Tactics' proprietary stability control software.

"It takes away the mechanical complexity of a helicopter and moves that complexity into the software," Jehangir says. "All the stability and control is done via high-speed computerized feedback."

The engine-rotor combos connect to a boxy fuselage on wheels, which houses a gasoline-powered automotive drivetrain complete with transmission, steering, and brakes. When the Black Knight transforms into drive mode, its engines and rotors fold up against the fuselage to yield an 8.5-foot-wide ground vehicle. Interior cargo volume is on par with the Army's UH-60 Black Hawk helicopter. And, Jehangir says, "you could fit at least three or four of these under the rotor diameter of a Black Hawk."

The foldable configuration means the Army could transport a Black Knight inside a C-130, and the transforming qualities don't end there. Advanced Tactics envisions substituting different fuselages and payloads beneath the lift system for different missions. Theoretically, its wheeled suspension could be replaced by skids, pontoons, or a hull.

"Conventional helicopters have their propulsion built into the fuselage, making it very difficult to change configuration," Jehangir says. "Our propulsion system is almost completely separate. There are just a few lines and wires connected to the fuselage."

Currently, the Black Knight can lift loads up to 500 pounds to a theoretical 10,000 feet. Turbodiesel propulsion could double the service ceiling and dramatically increase the payloads while offering range and duration competitive with other autonomous unmanned aerial systems.

Advanced Tactics completed autonomous drive testing in December 2013 and a series of short duration flight tests in March. The test flights were 10 to 30 seconds in duration with a remote pilot controlling power (and thus altitude). But the stability control performed autonomously.

The Black Knight arose from a congressionally funded 2010 design project for the U.S. Army's Telemedicine and Advanced Technology Research Center (TATRC) which sought a small unmanned aerial system (sUAS) for autonomous battlefield casualty evacuation. Along the way, Advanced Tactics also proposed the Black Knight for DARPA's Transformer TX program which sought a cargo vehicle that could fly and drive autonomously (though Black Knight was not selected for that DARPA program).

Along with obviating human risk, cost is a major driver in autonomous UAS cargo systems. Jehangir says the Black Knight's cost is "an order of magnitude" less than its conventional helicopter counterparts. The prototype was designed and built for less than $2 million. The company is offering Black Knight and other multicopter designs to several U.S. military branches and foreign customers.